


What I've Done

by Gemmiel



Category: Supernatural
Genre: 9.23, DeanCas - Freeform, Demon!Dean, Destiel - Freeform, M/M, do you believe in miracles
Language: English
Status: Completed
Published: 2014-05-15
Updated: 2014-05-20
Packaged: 2018-01-24 22:42:07
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 5,532
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1619594
Author URL: https://archiveofourown.org/users/Gemmiel/pseuds/Gemmiel
Summary: <blockquote class="userstuff">
              <p>Dean is completely taken over by the Mark of Cain. A speculative end of season 9/beginning of season 10 story. Possible spoilers for 9.23.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> I don't think this is a particularly new or unusual take on how events at the end of this season might unfold, but I felt the need to write it. I have it mostly written, and hope to have the rest up by tomorrow. It will be either two or three chapters long, depending on how I decide to break up the story. Warnings for some violence and gore (nothing excessive for Supernatural) and unpleasant thoughts in Dean's head. Title is from the Linkin Park song.

Metatron is dead.

The Scribe of God lies at Dean’s feet like a crumpled rag doll, blood oozing sluggishly from the numerous wounds in his chest. His grace has already drained away, flaring blue-white as it dissipated, and all that is left of the angel who wanted to be God is his shattered vessel. Dean stares down at him, his lips drawn back in rage and hatred, and thinks about how much he enjoyed killing the smug little bastard.

He loves killing.

He wants to kill again.

Unfortunately, Metatron’s troops scattered before Dean, Sam and Cas caught up with him, and there’s no one in this empty office building except the three of them. His brother, Dean realizes vaguely, is speaking to him. His voice is calm, gentle, but the words make no sense. Dean is caught up in something too great for words, something beyond mere speech. He is a creature of impulse now, a being of violence and bloody murder.

Sam is coming toward him, hand outstretched. Dean looks at him, tries to see the brother he’s loved and protected since Sam was a baby, but all he sees is a human to be slain, a life to sacrifice to the clawing hunger inside him. 

The Blade demands death, and Dean is its servant.

His lips draw back entirely, in a fearsome, animalistic snarl, a growling noise rolls from his chest, and he lifts the bloody Blade as the need to kill consumes him. Sam comes to a sudden startled halt, gaping in shock that would be comical, if Dean were capable of being amused. Sam is saying something, his lips moving in what is probably a desperate plea, but Dean doesn’t hear his words. All he knows is the savage impulse to tear and rend and destroy, surging inside him, roaring in his ears like the ocean.

 _Kill him,_ the Blade clamors. _Kill kill kill._

Waves of anger and hatred pour over Dean, flaring outward from the Mark seared into his arm, and he lets himself drown in them. He lifts the Blade higher, relishing the thought of the ancient weapon slashing through flesh and bone, reveling in the thought of his brother’s blood spurting across the floor. It's his destiny to kill Sam, just as Cain killed Abel so long ago. The thought of killing Sam feels right. It feels _good._

He knows, in a distant, remote sort of way, that Dean Winchester has always protected his little brother, that he would never voluntarily hurt Sam, let alone kill him. But right now, with the Blade singing inside him, none of that seems to matter.

Sam is prey, and prey must be slaughtered.

Dean swings the Blade, but suddenly something hurls itself between him and Sam, clutching desperately at his arm. Castiel, he realizes dimly. The angel has thrown himself between the two of them. Distantly, Dean can hear him yelling. 

_Run, Sam! Go on, get out of here!_

Dean’s strength is augmented by the Blade, and no human could possibly hold him back. Even angelic strength is no match for him, particularly not angelic strength that is fading daily as its owner’s grace is leeched away. But Cas tries, catching Dean’s wrist in his hand and struggling valiantly to push it back, away from Sam.

His mouth is moving, desperate words spilling from it, words that make no sense, sounds without meaning. _Dean—this is all wrong—fight it, Dean, **fight it** —_

Dean can’t imagine why he’d want to fight against this. This is who he is, who he wants to be. A terrifying force of destruction, walking the Earth, killing everything in its path, slaying the evil and the innocent alike.

At last, he's the hunter his father wanted him to be.

The lust for murder rises up inside him, too strong to be denied. He slams his fist into Cas’ mouth, hitting him over and over again, until the angel staggers backward, falling to his knees. Blood trickles from his nose and mouth, and he stares up at Dean with wide blue eyes.

Dean lifts the Blade.

Castiel is begging, and at first the words are as meaningless as everything else. _You’ll regret this later, Dean, don’t do it, please, it’s not myself I’m worried about, it’s **you.**_

 _Irrelevant,_ the Blade responds. _Kill. Kill._

Dean steps toward Castiel, imagining the satisfying feel of flesh and bone giving way beneath his Blade, anticipating the fierce, hot ecstasy of killing surging through him like heroin. He briefly regrets that the angel no longer has wings. Hacking off his wings, leaving him with bloodied, useless stumps, would have been so much fun. But hacking off his head will have to do…

 _This isn’t you._ The angel’s desperate words cut through the bloodlust that floods him. _I know you’re in there. I know you can hear me._

Dean hesitates. The Blade falters.

He’s heard these words before, somewhere.

 _Please._ The angel’s voice is low, and yet it rings out as clearly as the Blade’s demands do. _Please, it’s me. We’re family. We need you…. I need you…_

Under the influence of the strangely familiar words, the terrible thirst for violence begins to fade away. Dean lowers the Blade, and stands there, blinking in bewilderment as the rage mists slowly clear from his mind. Near the doorway, Sam is still standing, staring at him, wide-eyed and slack-jawed.

Dean stares back at him. Looks down at Cas, crouching bloodied and beaten on the floor at his feet. Shock and pain begin to roil in his chest, choking him.

He almost killed Sam. 

He almost killed Cas.

He's horrified to realize how close he came to slaughtering them both-- his brother, his best friend. His only remaining family. He wants to fling the Blade away, but he just _can’t,_ any more than he could throw an arm or a leg away. It’s become a part of him. In a way, it _is_ him. He is the Blade and the Blade is him, all tangled up together in a way he can’t explain. 

It’s too late for him, he recognizes bleakly. He’s a killing machine, totally under the Blade’s control. There’s nothing he can do, nothing anyone can do, to break the Blade’s power over him, not now.

All he can do is run away, far away, and make absolutely certain he can’t kill anyone he loves.

He turns and sprints for the window, the Blade still clenched in his blood-covered hand, and is outside in a spray of broken glass before Cas or Sam can react quickly enough to stop him. A few seconds later, he’s wrenching open his car, falling into the front seat, gasping, sobbing. The engine roars to life, and he hits the accelerator, fleeing from his friend and his brother. Gravel flies in his wake as he speeds away.

The Impala hits the two-lane road at ninety, and he speeds down the deserted dark road mindlessly, blindly. His destination doesn't matter, not really. All he wants is to be far, far away from the people he loves.

He glances into the rear view mirror to make sure Sam and Cas haven't hotwired a car to follow him, and his blood freezes with shock and horror.

His eyes are black.


	2. Chapter 2

**Notes for the Chapter:**

> Warnings for violence and violent thought processes in Dean.

They are hunting him. 

Dean knows perfectly well Sam and Cas are on his trail, even though he never catches a glimpse of them. He just _knows._ They’re after him, trying to track him down, just as he’d be after them if something like this had happened to them. They want to capture and cure him. And if that doesn’t work, they’ll do what they have to do… and kill him.

Assuming anything _can_ kill him.

Regardless, he doesn’t want them to try. Not for himself, but for them. Partly because he knows he might kill them both, just like last time. But also because both of them once loved Dean Winchester, unworthy as he was of anyone’s love, and neither of them should have to put him down like the rabid animal he now is. 

So in order to avoid the bad re-enactment of Old Yeller, he keeps running. He’s destined to wander, anyway. He knows that. The one who carries the Mark can never settle down, can never put down roots. For him, there will never be friends again, nor family, nor any possibility of love. All he has left is the Impala. All he can carry with him is the Blade, and the hot, craving hunger to kill everyone he meets.

There is still enough of Dean Winchester left in him that he doesn’t murder indiscriminately. He wanders cities and cleanses them of rapists, murderers, violent criminals. He kills vampires, werewolves, demons. And he only walks the streets at night so that when the bloodlust takes hold of him, there are fewer bystanders around. He knows how easily he could be tempted to take an innocent life.

Oh, God, he knows.

He’s slipping down the shadows of a dark alleyway, following a guy the cops want for murder, when a phone rings. Not his—he discarded his when he hit the road. Not only is it way too easy to trace someone with a cell phone, but it just doesn’t seem right for the new Father of Murder to be carrying an ancient jawbone in one hand and an iPhone in the other. Sounds kind of anachronistic. Unbiblical, even.

The guy looks back at the ringing sound, sees Dean in the shadows, and bolts. Whether he's warned off by Dean's wolfish demeanor, or whether he can see the inky blackness of his eyes, the hunter doesn't know. Dean growls with annoyance, but doesn’t bother pursuing him. The urge to kill hasn’t entirely overtaken him yet, and right now his curiosity is stronger than his craving for violence. 

He looks around for the source of the sound, and sees an old phone with a metal cord, the kind that used to hang in phone booths back in the pre-smartphone days. Still see ‘em in small towns sometimes, but rarely. It’s not connected, though, just tossed there in a pile of discarded junk.

It’s not connected, yet it’s ringing, shrilly and persistently.

He looks at it a long time, but the ringing doesn’t stop. At last he reaches down and picks it up. He doesn’t say anything, just presses it to his ear. The cord dangles uselessly, attached to nothing. He listens for a long moment. At last a voice speaks.

“Dean.”

Dean blinks, because it’s the last voice he ever expected to hear. “Cain?”

“You made me a promise,” Cain says. “Carry it out.”

Dean remembers. _Make me a promise first. When I call you -- and I will call -- you come find me and use the Blade on me._

It seems like a lifetime ago—it _was_ a lifetime ago, in a manner of speaking—but Dean hasn’t forgotten that he agreed. He growls again, a dangerous, feral sound.

“I don’t owe you a fucking thing, old man.”

“You owe me this.”

Yeah. Dean figures that’s true, actually. Cain is the one who gave him this Mark, who set him on this neverending path of slaughter, sent him forth to kill and destroy and mutilate. If anyone in this world deserves to die, it’s Cain.

He refuses to entertain the thought that he _asked_ for this, that at least some of the blame is his.

“Fine,” he bites out. “Where you at?”

Cain laughs, softly, almost maliciously.

“You’ll find me, Dean Winchester,” he says. “You’ll find me.”

*****

Dean gets back in his car and drives, without heading anywhere in particular, and by daybreak he finds himself pulling into the potholed parking lot of an old, broken-down motel. Not for him—he doesn’t sleep anymore. He doesn’t do much of anything anymore, except stalk and kill. But his forearm is throbbing like it does when he’s closing in on prey, and he knows he’s found Cain.

He picks up the Blade from the seat next to him, and walks to the long, low building, drawn like a magnet to its left side. Cain, he notes, is in room 6, on Route 66. Of _course_ he is. Dean might laugh at the grim humor, if he were capable of laughter any longer.

Dean tries to turn the doorknob. It’s locked, and probably bolted, but that doesn’t matter. He uses a touch of telekinesis (one of the many bonuses of being a demon) to manipulate the locks, then flings the door open and stalks inside.

Cain is seated in an uncomfortable-looking chair, waiting for him.

“Hello, Dean,” he says quietly.

Dean stares at him and doesn't say anything at all. He is very conscious of the burning skin along his forearm. Cain laughs softly, probably the only person on Earth who can't be intimidated by Dean's glare.

"Your brother and your angel contacted me," he says. "They are looking for you."

"Fuck 'em."

Dean knows his voice is lower and gruffer than ever, and if Cain had the sense God gave a gopher, he'd be cringing in fear. But he looks unmoved, presumably because he's done the Father of Murder gig himself. He speaks calmly.

"They can cure you, you know."

"No, they can't," Dean answers. Of course he and Sam stumbled across a "cure" for demons last year, but that's for ordinary demons. For him, a scary-ass, industrial-strength demon driven by an all-consuming lust for blood-- well, who knows if it'd work on him? And besides, the chance of Sam and Cas getting their hands on him without losing their lives in the process is remote. 

Cain only smiles serenely.

"I didn't think you'd go back to them of your own accord," he says. "But sooner or later they'll catch up to you, and then-- then you'll kill them."

Dean can't hold back the faint quiver that runs through him. There is still enough human left in him that the idea of killing his brother and Cas appalls him. But in another two weeks? A month? A year?

He can feel the remaining bit of humanity draining away, can feel himself turning cold and remote and heartless. Moment by moment, he's less and less human, and it scares the hell out of him.

Well, no, it doesn't. There's no way of getting the Hell out of him, not now. He frowns at Cain and lifts the Blade tauntingly.

"Don't you want this? Aren't you going to fight me for it?"

"Not anymore." Cain pushes up the sleeve of his shirt, exposing his forearm. The Mark is still there, but it's faded to white, puckered like an old scar. Even in the presence of the Blade, it doesn't burn.

"Nice," Dean sneers. "You passed the damn thing on to me, and got rid of it."

"You could do that, you know." Cain stares at him steadily. "Find a sucker to take it off your hands, so to speak. Maybe some prostitute who's tired of being abused. Maybe some kid who gets beat up all the time, and who'd like to get revenge on his tormentors. You could transfer it over to someone else. And then... then you could go home."

 _Home._ Dean thinks about going back to the bunker, back to his little makeshift family, and a wave of longing hits him, so intense it almost drowns out the burning of the Mark for a moment. But he shakes his head.

"I'm not you," he snarls. "I'm not passing this off to someone else. I chose it, and it's my fate now. Not some other poor fucker."

"Besides," Cain drawls, "you'd hate to give up the killing."

Part of Dean knows that's the truth. The pleasure the Mark gives him is so incredible that he hates the idea of losing it. But the other part of him, the human part that's rapidly receding, is indignant to have his good intentions taken for bad.

"I'll be damned if I'll pass this curse onto anyone else," he snaps.

Cain studies him a moment longer, then his mouth curves faintly beneath the salt-and-pepper beard. "I was right," he says softly. "You are worthy."

He _is_ worthy, and he knows it. The Mark couldn't have found a better man to carry it. He's a killer. He's always been a stone-cold killer. And damned if he won't prove it again. 

He snarls at the other man. The Mark burns, sending its poison into him, and he feels the powerful high that only comes when he’s edging closer to another kill. He closes his eyes for a moment, savoring the sensation, and then opens his eyes and lifts the Blade.

Despite his addiction, the craving to kill that has gripped him, a desire as fierce, as compelling as heroin, he really doesn’t want to do this. Despite Crowley’s cringing terror of the man, despite the fact that Cain gave him the Blade and turned him into… into _this,_ he kind of liked Cain when they first met. Felt a sort of kinship with the guy, really. He lived alone and he couldn’t put down roots and he didn’t dare make a real relationship with anyone. Dean can relate.

But no matter what he himself wants, he can’t stop this. He doesn’t want to enjoy watching the Blade cut through Cain’s flesh, seeing the crimson blood spurt everywhere, but he can’t help it, can’t help reveling in the bloodlust burning through his veins. The Blade has turned him into this. A monster. 

A black-eyed demon.

He’s spent his life killing demons, fighting them, and now he’s become one. Dean Winchester is fading with every kill. No, he's gone, lost, and there’s nothing left inside his body but a demon, eyes as black as the Impala’s paint. 

But of course he always knew he’d wind up here, somehow or other. 

It’s what he deserves. 

Even through his newly black eyes, Dean can see peace and acceptance in Cain’s gaze. This, he knows, is what Cain wanted. After so many years cursed to roam the Earth, he longs for an ending, and perhaps a new beginning. For him, death is freedom. 

Maybe he’ll see his Colette again. The little part of Dean that’s still human hopes so.

Cain doesn’t beg, doesn’t ask for mercy, doesn’t say anything else. He just watches calmly as Dean approaches.

The Blade separates Cain’s head cleanly from his shoulders. His head tumbles to the ground and rolls along the carpet. Even though Cain is dead, Dean raises the Blade again. He loves this part, loves slamming the sharp point of the Blade into his victim’s chests, over and over again, until the corpse is mutilated beyond recognition, until he’s splattered with their blood. When he’s covered in someone else's blood, when a mangled body is lying at his feet, the high is so intense that it’s better than anything he's ever experienced.

He raises the Blade… and then lowers it, drawing in a startled breath.

The awful demonic power that has filled him is ebbing.

He opens his fingers and lets the Blade drop away. He watches it fall onto the cheap industrial carpeting, just as Cain’s head did, and he can see somehow that all the terrible magic has drained away from it. It’s nothing but an old bone. He can’t feel its call, doesn’t feel the compulsion to hold it close to him, to hide it away and carry it with him always, to slaughter with it.

Shocked, barely daring to hope, he rolls up his sleeve and looks at his forearm. 

The Mark is fading.

As he watches, it fades to nothingness, leaving no scar behind. He stares in stunned silence at his bare forearm for long moments. He doesn’t have to look into a mirror to know that the blackness has drained away from his eyes as well.

When Cain died, the Mark died as well. 

Cain, he thinks slowly, must have known that would happen. That was why he'd extracted a promise from Dean. That was why he’d insisted Dean come and find him. Not for Cain’s sake, but for Dean’s.

Cain had saved him. 

His eyes begin to smart, and he drops to his knees next to Cain’s lifeless corpse, buries his face in his hands, and weeps with relief and profound gratitude.

At last he gets unsteadily to his feet and makes his way to the parking lot. The Impala is waiting for him, as she always is. He settles into the driver’s seat, pats her wheel affectionately, and looks into the rear view mirror.

Green eyes look back at him. An impossible relief fills him as he turns the key.

And starts for home.


	3. Chapter 3

When Dean walks into the bunker, Sam and Cas splash him with holy water, and when he doesn’t react (beyond an indignant sputter or two), they practically fall on him, wrapping their arms around him and smothering him like they haven’t seen him in years. Dean knows he doesn’t deserve their affection, not after he came so close to murdering them both, not after he’s killed and killed again over the past two weeks, but he lets himself be drawn into their embrace. Cas even presses a surreptitious kiss or two against his neck, and Dean still doesn’t protest. He can feel tears on the angel’s cheeks, and the knowledge that Cas was that broken up about him leaving, that worried about him, warms him.

And _Sammy._ Well, he and Sam have been at odds lately, and what with the Blade kind of taking him over, they haven’t had a lot of chances to work all their crap out. Dean knows that their issues run deep, and they won’t be fixed in an hour, or a day, or a week. But he’s profoundly grateful to Cain for giving him a second chance to work things out with his brother.

Sam’s cheeks are wet too. Or maybe Dean’s the one who’s crying.

“Cain,” Dean says, or tries to. His voice breaks before he can even finish the word, let alone get a sentence out. Sam brushes his hair in a gentle, paternal gesture that Dean recognizes as the way he himself touches Sammy’s hair when his little brother is hurt or ill.

“We know,” he says. “We couldn’t find you, but we did manage to find him. We told him you’d become a demon, that you were lost to the Blade, and he said he’d do what he could.”

“But he’s—"

“We know.” Now it’s Cas’s turn to touch his hair. It’s like they can hardly believe he’s real. “He told us what he was going to do. It’s all right, Dean. This is what he wanted.”

Dean is a little relieved to hear that. Looking into Cain’s eyes, he’d known it, but it’s a relief to have it confirmed. He has so many more questions to ask, so much to catch up on, but the words are lost in a cavernous yawn. In the safety of the bunker, with the people he loves, he discovers he’s terribly tired. He hasn’t slept in two weeks. Demons don’t need sleep, but humans do. And he’s only human now.

Sam and Cas recognize how exhausted he is, and the two of them wrap their arms around him and lead him toward his bedroom. Before he knows it he’s being tucked in like a baby, too weary to put up any sort of objection. His eyes are so blurred with exhaustion that he can barely look around and see the familiar walls, the shelf lined with objects he loves, his weapons, his record collection, his Vonnegut books. 

When he wakes up, he promises himself, he’s going to lie in here for hours. He's just going to revel in being _home._

But right now, all he has the energy to revel in is sleep. He closes his eyes, and the last things he feels are Sam’s hand squeezing his shoulder, and Cas’ lips brushing against his cheek.

Sleep is all he knows for a long, long time.

*****

As he drifts toward a waking state, he begins to dream of the people he killed over the past two weeks, while the Blade held him in its thrall. He’s grateful that he hadn’t slipped far enough into the darkness to kill innocents. But even so, in his dreams he feels guilt. Werewolves and vampires are one thing, but to kill humans—it’s a line he’s always tried not to cross.

He’s a murderer, and that knowledge makes him toss and mutter in his sleep.

“It’s all right, Dean.”

The voice is deep and gentle, and it pulls Dean from his uneasy slumber. He opens his eyes to find himself sprawled on his bed, his skin wet with sweat. Someone pulled his shirt off at some point—probably because it had been caked in blood—and he’s shirtless and barefoot, wearing a pair of jeans and not much else. Next to him, Cas is stretched out, wearing a t-shirt and jeans, his hand gently stroking Dean’s hair.

Dean almost jerks back reflexively and snaps, _Personal space, dude!,_ but… well, Cas’ hand in his hair is oddly comforting. He lets himself relax into it.

"Where's Sammy?" he mumbles.

"Sleeping. He hasn't gotten much rest over the past couple of weeks. But you'll see him later, don't worry."

“I tried to kill you,” he mutters, closing his eyes. "You and Sammy both."

“That wasn’t you. Not really.”

“It _was_ me.” He remembers the way he’d held the Blade high, with every intention of lopping Cas’ head off, and he shudders, burying his face in the pillow, his guts writhing in shame and guilt.

“No,” Cas says softly. “No more than it was my fault when Naomi used me to try to kill you. It wasn’t you. It was the Mark and the Blade, controlling you.”

“I’m the damn fool who took them on in the first place.”

“Hubris,” Cas says, his voice gentle and understanding. “You thought you could handle them, control them. Instead they controlled you. Hubris has led to disaster for me more than once, Dean, and for many others. There’s an old saying: Pride goeth before a fall.”

Dean figures Cas knows all about hubris, perhaps better than anyone else on the planet. Still, he can’t accept the absolution Cas is offering. “I screwed up.”

“You did.” Cas’ voice is serene. “Most people have, at some point in their lives.”

Dean knows the angel is thinking about his own mistakes. “Cas?” he asks, very softly. “How do you get past the bad things you’ve done? How do you… forgive yourself?”

“You just… go on.” Cas’ hand is in his hair again, stroking gently, and Dean doesn’t object. In fact it seems natural somehow, like Cas has always touched him this way. Like he and Cas have always been this intimate. “There is nothing we can do to change the past, Dean. You know that. We can only go forward and try to make the future better.”

Dean lifts his head from the pillow to find Cas only inches away, blue eyes shining. Cas’ hand moves down to his shoulder. His palm feels warm against Dean’s bare shoulder. Warm… and alive.

“Cas?” he whispers. “Are you really dying?”

“I do not believe so,” Cas responds. “At first I thought I would. I was not certain I could survive the loss of the stolen grace. Grace is not meant to be used that way, and I could feel it eating away at my insides, gnawing at me like cancer. But to my surprise, the adverse effects drained away with the grace. It is now almost entirely gone, and I am clearly not dying. I simply feel…” He sighs. “Empty.”

“I’m sorry.”

“Strangely enough, I am not. Well… I confess I will miss my angelic powers. The ability to heal, or to smite demons, is not something I would lightly toss away. But it does not pain me to think of myself living out my life as a human. As a mortal.” He smiles slightly. “I would not choose to be immortal, Dean, when you are not.”

That declaration is so huge that Dean doesn’t even know what to do with it. He can feel his cheeks flushing, and he blinks and looks away from the honest blue eyes watching him. Glancing around the room, he sees Cas' stuff mixed in with his own—the familiar beige trenchcoat hanging over a chair, a few books of modern poetry on the shelf, a small collection of bird feathers and leaves. Cas seems to have moved into Dean's room, and _that's_ huge, too. His cheeks heat further, and he decides it’s safest to turn the conversation in a slightly different direction. “I feel kind of empty too,” he admits.

“The loss of the Mark,” Cas says, nodding. “I was concerned that would be the case, that you would experience a sort of withdrawal.”

“Kind of, I guess. It’s not like drugs, though. I don’t feel sick or… or cravings, or anything. I just feel like something’s missing.”

He can’t explain it, can’t properly describe the sensation of a vacuum deep inside him, an emptiness that needs to be filled. But Cas seems to understand.

“That’s a normal reaction,” he says. “I told you once that when a claim is laid on a living soul, it leaves a mark. The Mark was such a claim—albeit an evil one—and now that it is gone, you feel its lack. And if something does not take its place, then you will seek to fill the emptiness with something else. Drugs. Alcohol. Sex.”

“So… back to normal?”

“This is not a joke, Dean.” Cas frowns at him. “Sex is generally harmless, and can even be beneficial, but neither Sammy nor I wants to see you turn to artificial substances again. I may be able to help, but I have so little grace left…”

“No,” Dean says instantly. “You’re not using up the last of your grace on me, Castiel.”

Cas rolls his eyes. “It is not a savings account, Dean. If I do not use it, it will drain away in any event. I might as well use the last remnants on something worthwhile.” 

He studies Dean for a long moment, then reaches out and puts his hand on Dean’s left shoulder. He frowns in concentration, and Dean can feel the power crackling in the room, like lightning sizzling through the atmosphere. The lights flicker and spark, reminding him of the very first time he met Cas.

Cas’ palm against his shoulder seems to sear into him, and he utters a startled yelp. Cas pulls his hand away, and Dean looks down at his bare shoulder and sees a handprint there. It's the same mark that was burned into him when Castiel first dragged his unworthy ass out of Hell, a mark that long ago faded away, and yet is clearly visible on his shoulder once again.

“Cas,” he whispers, in something approaching awe. “Did you lay a claim on my soul?”

Cas smiles slightly. “The claim was already there, Dean. I simply… renewed it. You now carry the very last of my grace inside you. Because it is etched onto your soul, it is unfading and eternal, and it should ease your emptiness.”

“The very last—are you telling me you're human now?”

“I am…” Castiel blows out a breath. “Fallen.”

“Being fallen’s not so bad.” Dean moves a hesitant hand toward Cas and gingerly places it on the other man's chest. He watches with interest as Cas’ pupils dilate. “I mean… it has its advantages.”

“Does it?” The ex-angel's mouth curves in a small smile. “Perhaps you should show me these advantages, Dean.”

Dean hesitates. He’s not good enough for Cas, not nearly good enough, and he knows it. After everything he’s done, all the lives he’s ended, after he nearly killed both Sam and Cas…

Sam, he knows, has already forgiven him for what he's done. Despite all the anger that has sizzled between them over the past months, Sam has already forgiven and forgotten, because that's what brothers do. But what about Cas?

In his mind, the former angel's words echo. _There is nothing we can do to change the past, Dean. We can only go forward and try to make the future better._

He looks back at Cas, and sees the blue eyes watching him with understanding and patience and unmistakable affection. The look in those eyes warms him, comforts him, _fills him,_ even more than the mark on his shoulder does. If anyone on the planet understands him, he thinks, if anyone can possibly grant him forgiveness—it’s Cas. Castiel knows the full terrible measure of his sins, in Purgatory and Hell and on Earth. And yet Cas’ friendship—his love—is unconditional. Unshakable. Dean knows that as surely as he's ever known anything. 

He lets the corners of his own mouth curve in an answering smile.

“I'd like that,” he says, and pulls the fallen angel in for a kiss.


End file.
